[19:07:02 WARN]: [Murder] Task #2211 for Murder v5.9 generated an exception
java.lang.IllegalArgumentException: Name cannot be null
        at org.apache.commons.lang.Validate.notNull(Validate.java:192) ~[craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at org.bukkit.craftbukkit.v1_8_R3.CraftServer.getWorld(CraftServer.java:1014) ~[craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at org.bukkit.Bukkit.getWorld(Bukkit.java:496) ~[craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at me.joseph.murder.Main.getSpec(Main.java:1586) ~[?:?]
        at me.joseph.murder.Arena$3.run(Arena.java:803) ~[?:?]
        at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71) ~[craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:723) [craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [craftbukkit.jar:git-Spigot-5f38d38-18fbb24]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_131]